Flood frequency analysis with consideration of hydrological.pdf

Under coupled influences of human activities and climate change, hydrological alterations are unavoidable
and should be addressed in the evaluation of flood risk. In this study, the flood risk in the Pearl River
basin, one of the economically developed regions in China, is investigated, based on long term annual
maximum series (AMS) from 28 hydrological stations. Results indicate the following: (1) significant
hydrological alterations have been identified and alterations of precipitation extreme regimes are one
of the pivotal factors triggering hydrological alterations of AMS, as abrupt changes of precipitation
extremes occur is similar to that of the AMS in time and space. In the East River basin, however, massive
human withdrawal of freshwater, a number of water reservoirs and other hydraulic facilities combine to
reduce the flood risk. (2) High flood risk can be found in the upper and middle West River basin and the
North River basin with an increasing magnitude of 0–40% and 10–30%, respectively. Besides, frequencies
of flood events with return periods of longer than 20 years are found to be significantly decreasing. In the
East River basin, however, the frequency of floods with a return period of 20 years is increasing, but the
flood volume is greatly decreasing. (3) Higher flood risk due to alterations of hydrological extremes will
pose a threat to the existing hydraulic facilities. Furthermore, the higher flood risk in the West River and
North River basins will potentially threaten the Pearl River Delta, a densely populated region with highly
developed socio-economy. The results of this study will thus be of great value in developing measures for

resilience to natural hazards in high development economic and coastal regions.